Let I = ∫xlog x dx
Taking log x as first function and x as second function and integrating by parts, we obtain
I = log x∫x dx - ∫{(\(\frac {d}{dx} log\ x\))∫x dx} dx
I = log x . \(\frac {x^2}{2}\) - ∫\(\frac 1x\) . \(\frac {x^2}{2}\) dx
I = \(\frac {x^2log\ x}{2}\) - ∫\(\frac x2\) dx
I = \(\frac {x^2log\ x}{2}\) - \(\frac {x^2}{4}\) + C
Let \( f : (0, \infty) \to \mathbb{R} \) be a twice differentiable function. If for some \( a \neq 0 \), } \[ \int_0^a f(x) \, dx = f(a), \quad f(1) = 1, \quad f(16) = \frac{1}{8}, \quad \text{then } 16 - f^{-1}\left( \frac{1}{16} \right) \text{ is equal to:}\]

The number of formulas used to decompose the given improper rational functions is given below. By using the given expressions, we can quickly write the integrand as a sum of proper rational functions.

For examples,
